Music Thing Modular Turing Machine can do a lot more with expanders. The most popular is probably Pulses.

Pulses

The earlier version of Pulses had seven outputs, but Pulses II adds four more, made up of logical ANDs of the seven (1+2, 2+4, 4+7, 1+2+4+7).

Pulses MkII is very simple. I didn’t need a build guide. It consists of eleven jacks and LEDs. On the PCB are 22 SMD resistors plus one quad CMOS AND chip. The expander connects to TM MkII by a 16-pin IDC cable (supplied), identical to a 16-wire Eurorack power cable. There’s a one-to-one correspondence between the Turing Machine LEDs and the pulse outputs. Pulse width of all outputs matches the pulse width of the CLOCK input.

Vactrol Mix

Connecting to the TM GATES header, it’s a 4-in, 2-out matrix mixer controlled by the Turing Machine. Each input has a buffered attenuator that feeds to the left and right mix, controlled by two gates. Thus the signal may be sent to the left, the right, or to neither output and you can manually control the level of each input. (The double output per channel is just a multiple.) An envelope is created by the response of the vactrol. This creates rhythmic patterns or shifting drones from any audio source. It’s DC coupled, too, so you can also rhythmically cut up DC sources like LFOs or envelopes.

Demo sounds

I made a simple patch, consisting of three Vactrol Mixed sounds. The Turing Machine stepped CV out is controlling the pitch of the sources, and one of the Pulses MkII outputs is triggering one of the sounds.